Figures from OpenSecrets.com show that Lynch took in a whopping $464,175 in PAC donations during his 2011-2012 election cycle, making up the majority of his donations – 64 percent.

Markey took in plenty, but not as much as his opponent. Forty percent of Markey’s donations – or $434,228 – came from PACs in the same time period.

The two candidates will face off in a primary on April 30th before the special election on June 25, 2013 to fill the empty US Senate seat left by John Kerry, who is now the US Secretary of State.

Professor of politics at Clark University, Srini Sitaraman says that the even after the Citizens United U.S. Supreme Court decision, special interest money is not going to go away.

“I think advocacy groups are going to pump a lot of money into this campaign,” he said. “But this year the campaign has not really heated up, at least so far. This may be because there is a bit of fatigue out there and people are not as energized as they should be. If that is indeed the case then maybe you are going to see greater involvement of advocacy groups in this particular election.”

Larbor Groups Carrying Weight

Between the Democratic representatives, political experts agree that they will fight the hardest to gain the backing of large labor unions.

“The big question is where labor unions will fall out. Both of them will be trying hard to court the labor vote in this primary election,” said Mark Miller, professor of politics at Worcester’s Clark University.

“[Markey] will split labor support with Lynch, drawing support from public employees’ unions,” said the Clark professor.

While many saw this as a huge blow to Lynch, Sitaraman said that he still has a lot of appeal to these groups.

“I anticipate labor groups playing a bigger advocacy role in supporting Lynch; while Markey is more likely to be the establishment candidate,” he said. “This might provoke the interest groups to gravitate towards Markey because if they believe he is going to win, then they better start the lobbying right now.”

Boatright said he assumes Lynch will take in more from blue-collar unions this cycle.

Broken down into industries, Lynch received the most money from Public Sector Unions, which provided $131,000 in PAC donations. Building Trade Unions ($69,500), Industrial Unions ($38,000), Securities & Investment ($35,000), and Lawyers/Law Firms ($20,500) made up Lynch’s top five industry PAC donations.

Markey’s Money

While Lynch’s sources were primarily from unions, Markey’s sum of PAC donations came primarily from Lawyers/Law Firms, who shelled out a total of $115,164 for Markey, including both PAC and individual contributions.

“Markey should be able to raise more money – from other politicians, from environmental groups, other left-leaning advocacy groups. Clearly has great expertise on a variety of issues,” said Boatright. “Markey has a long track record in Congress on energy-related issues, telecommunications policy, air quality, and other rather technical issues. He’s had a reputation as a very serious lawmaker, and many groups appreciate that.”

Lobbyists were the second highest grossing industry for Markey, with a total $79,950. $45,000 in PAC money came in from TV/Movies/Music, and the Real Estate and Telephone Utilities industries also pumped in tens of thousands of dollars, making up Markey’s top five highest paying industries.

Specifically, Markey’s top contributors broke the bank for him in his last election cycle. Fresenius Medical Care, which hires lobbyists, gave a total $20,200, followed by lobbying firm, WilmerHale LLP, with $20,000.

Time Warner and Time Warner Cable also paid over $10,000 each to Markey.

Bringing in the Green

Many in Markey’s top list were energy management companies, showing an ongoing trend of support.

“Markey has long been the darling of environmental groups,” said Miller.

And this trend isn’t going away this election cycle. The League of Conservation Voters announced recently that it intends to spend at least $650,000 for Markey’s field campaign.

No Outside Ad Money

While PACs are funding the Dem opponents left and right, the two agreed to sign a pledge to keep third party advertisements out of the race. Lynch and Markey said that outside influence has no place in the Massachusetts Senate race and called on the GOP to do the same.